The usage-centered design approach to UX design (as defined by Constantine & Lockwood) has been always a reference to me. Their articles describe practical well-defined techniques which I think can (and should) be included in development processes, and my humble opinion is that it deserves more attention than it gets.

Usage-centered design itself has been viewed as providing already established and effective methods for putting activity-centered design into practice and for overcoming some of the stated shortcomings of human-centered design (Norman, 2006).

Actually, I used their descriptions of techniques for Personas, User Roles and (Abstract) Use Cases as the basis for their implementation into UCDmanager. One of the main reasons for this choice is that they set the basis for a design methodology which includes different interrelated techniques, instead of the toolbox of heterogeneous independent methods we usually have.